Hello @peterz11, 

Are the costs you check for calls or mobile data usage? Remember that incoming calls, if answered by voice mail, are also charged, for example.

Learn all about roaming in the United States of America at nos.pt.

We suggest that you also consult the detail of your invoice through the NOS Customer Area or NOS App to better understand what the amounts are related to. Find out how at:

All communications made in roaming are the responsibility of the international operators to which you connect, with NOS being subject to the information made available by them.
Thanks

Thanks Mario for tutorials!  I am not sure if they will help me.  My question to you as the NOS guys here (19399 answers in this forum) is what should I do to stop the charges in the future. I plan to be here couple more months?  I have to admit in the first day I called Uber to pick me up from Denver airport. The invoice says: 

Consumos adicionais
Comunicações nacionais 23 jun - 22 jul €1,417 Consumos extra de telemóvel.
Roaming 23 jun - 22 jul €32,508
Tráfego de dados em roaming 23 jun - 22 jul €61,511

       Tráfego de dados em roaming
       (dados)
       9 MB €61,511
Créditos e débitos
Net Roaming 11 jul €7,500
Total telemóvel €102,94

9MB of data for 61 euro?

Ensure that the mobile phone is in flight mode, that is, that the card does not connect to the operator's network. This is because outside the European Union, there are costs, whether in the use of mobile data or even in incoming communications such as calls (even if you do not answer) or SMS.

In these countries, not wanting costs to exist, we suggest that you acquire a local card temporarily, @peterz11. 

Best ragards, 

Mario - this is what I did. This is not the first time I am in this situation. The phone was on just to call Uber and I also responded with SMS to get flat rate of $7.50 for a day.  Now NOS charged me $7.5 and a $100 for 2h of roaming.  This should not have happened. The phone is in airplane mode since then.  Now to make sure I removed NOS SIM card from the phone completely.  Do you know if that $100 charge can be disputed? 

Notoriously, his equipment was connected to the network of another operator, otherwise he would not have communicated to NOS that there was consumption. Right, @peterz11 ?
Consult the costs of using roaming in the country in which you are located. The Net Roaming service is intended to provide more affordable mobile data rates.

Thus, it starts to consume 200MB for a fixed amount of €7.5 instead of, for example, €6/MB in most countries outside the European Union.
This plafond is only available for 24 hours and if it runs out, if you do not activate another one, the amount charged will be the agreed commercial value
Best regards,

> Notoriously, his equipment was connected to the network of another operator, otherwise he would not have communicated to NOS that there was consumption. Right, @peterz11 ?

@Mário P. are you asking me if my NOS phone used in Denver to get Uber was connected to US mobile operator network?  The answer is yes unless NOS has cell towers in Denver :-)

> Consult the costs of using roaming in the country in which you are located. The Net Roaming service is intended to provide more affordable mobile data rates.

> Thus, it starts to consume 200MB for a fixed amount of €7.5 instead of, for example, €6/MB in most countries outside the European Union.
> This plafond is only available for 24 hours and if it runs out, if you do not activate another one, the amount charged will be the agreed commercial value
> Best regards,

@Mário P. My question to you still stands: why NOS is charging me for roaming and data on top of the ‘one day’ $7.50 charge?  The phone was tuned off for the rest of the month.  Who do I complain to get this $100 charge off of my invoice?

You can consult all the consumptions carried out in the NOS App, the amount is due, if you use the mobile internet service abroad it is understandable that there are costs. However, if you wish, send us a private message to the @Fórum  profile with your customer number. 
Thenks